Blood group training helping in surgery (9)
I believe the answer is:
operation
'surgery' is the definition.
(I know that surgery can be written as operation)
'blood group training helping' is the wordplay.
'blood group' becomes 'O' (O is one of the main blood groups).
'training' becomes 'PE' (Physical Education).
'helping' becomes 'ration' (a ration is a serving or helping).
'o'+'pe'+'ration'='OPERATION'
'in' is the link.
(Other definitions for operation that I've seen before include "Action; process" , "management" , "Handling" , "Surgical or military piece of work" , "Act of surgery" .)